Preparation of well drain holes for production



rag-km Jan. 22, 1957 PREPARATION OF WELL DRAIN HOLES FOR PRODUCTION 35 118 W i 11 l E p I 12; l E

' E i E J. S. M CUNE ET- AL Filed June 22, 1953 INVENTOR.

ATTORNEY.

PREPARATION or WELL niiAiN HOLES FOR PRODUCTION Iiohn S. McCune and William E. Hanks, Long Beach, Calif., assignors to Oilwell Drain Hole Drilling Co., Long Beach, Calif., a corporation of California Application June 22, 1953, Serial No. 363,029

7 Claims. (Cl. 2551.6)

This invention relates to improved methods and apparatus for lining well bores and preparing them for production. in certain respects, the invention is particularly concerned with the lining of auxiliary well bores or drain holes, i. e. bores extending laterally or generally horizontally from a main bore into the surrounding formation.

Before placing in production a well having one or more laterally extending drain holes, it is desirable to provide some means in the drain holes for preventing inward collapse of their walls. For this purpose, we advance into each drain hole an elongated longitudinally flexible liner, which retains the walls of the hole against collapse, and contains wall apertures spaced along its length for passing fluid into the hole from the surrounding formation.

A major object of the present invention is to provide a tubular unit which is adapted to serve the above drain hole lining function, and in addition is so constructed as to filter sand or other materials from the well fluid when the well is in production. Preferably, the liner is adapted to function also as a flexible drill string, so that it may first be utilized to drill a laterally extending drain hole, and may then be left in the hole as a combined liner and filter unit, when the well is put in production.

structurally, a unit embodying the invention includes a tubular preferably flexible body having wall apertures, and a mass of filter particles, typically gravel, carried by the tubular body and through which the well fluid flows when the well is in production. For best results, the gravel or other filter particles are carried at the inside of the tubular body. The body itself may be formed of a series of articulately interconnected sections, the lower of which desirably carries a rotary drill bit. When thus provided with a drill bit at its lower end, the unit is capable of actually drilling the hole which it is subsequently to line. Even if the hole has already been drilled, we frequently find it desirable to provide the device with a drill bit, in order that it may act to drill or ream out any cave-ins which may be encountered in the hole.

To provide for fluid circulation during lowering of the unit into a well, the unit may include a hose acting to deliver circulation fluid downwardly along the unit toward its lower end. This hose is preferably received within the tubular body, though in one form of the invention we contemplate positioning the hose about the body. The hose is desirably formed of a material which is adapted to disintegrate when subjected to the well fluid, so that the hose disintegrates when the well is put in production, to thus avoid restriction of the fluid path in the well by the hose.

The elongated unit is lowered into the well at the lower end of a tubular upper section or string, which is so attached to the unit as to be disconnectable therefrom by manipulation of the string from the surface of the earth. Such manipulation may also disconnect the cir- -nited States Patent 2,778,603 Patented Jan. 22, 15957 2 culation hose from the tubular lowering string, so that the string may be removed from the well while leaving the liner body, filter mass and hose in the well.

The above and other features and objects of the present invention will be better understood from the following detailed description of the typical embodiments illustrated in the accompanying drawing, in which:

Fig. l is a fragmentary side View of a drain hole drilling and lining unit embodying the invention;

Fig. 2 is an enlarged fragmentary vertical section through the joint interconnecting the upper and lower drill collar sections of Fig. 1;

Fig. 3 is an enlarged fragmentary vertical section through the drill bit and lower portion of the drill collar in Fig. 1;

Fig. 4 is a fragmentary partially sectional view showing the manner in which gravel or other filter particles are filled into the lower section of the drill collar of Fig. l; and

Fig. 5 is a fragmentary partially sectional view of a variational form of drill collar embodying the invention.

Referring first to Fig. l, we have shown at 10 the main vertical bore of an oil well, into which has been lowered a whipstock ii. The whipstock has an upper tubuluar portion 12, beneath which it presents an inclined laterally curving deflecting face 13, for deflecting a flexible drill collar laterally, to drill a progressively laterally curving drain hole 14. The flexible drill collar is formed of a pair of disconnectable upper and lower flexible sections 15 and 16, and carries a conventional rotary drill bit 1'7 at the lower end of the lower section. The upper end of upper section of the drill collar is connected to the usual tubular drill string, comprising a large number of pipe sections 118 interconnected at threaded joints 119 and extending downwardly from the surface of the earth.

Each of the sections 15 and 16 of the flexible drill collar preferably comprises a series of essentially rigid relatively movable tubular segments, movably interconnected by loosely interfitting lobes and recesses at their engaging ends 18. As will be understood, these articulately interconnected segments may be formed from conventional drill pipe or other pipe, by cutting the pipe at longitudinally spaced locations along circularly extending curving lines, whose curvature is such as to form lobes and recesses of the illustrated general configuration. Each of the individual segments of the flexible drill collar preferably carries an annular anti-friction bumper ring 19, typically made of rubber or other resilient material, for engaging the whipstock and well bore during advancement of the drill collar, to prevent excessive wear of the segments themselves. The lower flexible drill collar section 16 contains apertures 20 in the walls of its various segments, for passing fluid from the earth formation into that section of the drill collar when the well is placed in production.

The upper and lower sections 15 and 16 of the drill collar are detachably interconnected by a joint 21, in a manner such that clockwise rotation of the upper section is transmitted to the lower section during drilling, while the upper section is disconnectable from the lower section by counter clockwise rotation after completion of the drilling process. This connection includes a connector element 22 attached by a right hand threaded connection 23 to the lower end of the upper section 15 of the drill collar. Element 22 has an externally cylindrical portion 24 projecting downwardly into the upper end 25 of lower section 16 of the drill collar. The external diameter of portion 24 of connector element 22 is very slightly smaller than the internal diameter of the engaged upper portion of drill collar section 16, to be vertically movable into and out of its Fig. 2 connected position. At a pair-of diametricallyoppositelocations, the lower portion of element 22 has a pair of laterally projecting pins or lugs 26,'which are insertable into a pair of diametricallyopposite J slots 27*formedin' the wallof upper portion ZS-of-the lower drill collar section 16. As best seen iii-Fig. l,-each of these J slots extends first axially downwardly from' the upper end of part 25, and then extends circularly in a clockwise direction, as seen from the top of the wall. Inmaking the connection between the two drill collar'sectio'ns,-pins 2d are first slid downwardly within their respective J slots, following which the upper section15of'thedrill-collar is rotated in a clockwise direction relative to the lower section 16, to move pins 26 into the circularly extending portions of the J slots. The connections will then act to transmit clockwise rotary motion between'the upper'drill collar section and the lower-section, while beingdisconnectable by counter clockwise rotation of the upper section.

For conducting circulating fluid to the drill bit 17 during a drilling operation, the lo'wer'section 'lfi of the drill collar contains a'flexiblefluid passing hose 28, extending along the center of the lower section of the drill collar for substantially its entire vertical extent. At its upper end, this hose is attached by a clamp-29 to -a pipe 30 extending' axially at thecenterof the upper tubular portion 25 of the lower drill-collar section. Pipe 30 is connected in fixed relation to portion 25 ofthe drill collar, by welding or other attachment to a number of circularly spaced radially extending web'elements31, whose outer ends are welded to drill collar segment-25. A central bore 32in connector'element 22 slidably receives the upper end of pipe 30, when the J slot connection is made between the two sections of the drill collar. Pipe '39 thus receives circulating fluid pumped downwardly from the surface of the earth through the drill string and upper section l5 of the'drill collar, and passes the circulating fluid intohose 28 for delivery to the bit. The lower end of hose 28 is connected by a clamp 33' to a pipe 34, which is connected into bit passage 35 leading to the end of the drill-bit at 3-6.

Hose 28 is preferably made'of a materialwhich is disintegrable by thewell liquid-which fiows'into drain-hole 14 from the surrounding earth formationwhenthe well is in production. That-is, the hose material is disintegrableor solublelirr oil, andfor 'this'rea'son rriay 'be formed of crude rubber; or oil base by products.

About hose 23,'lower secti'on l6-of the drill'collar contains an annular mass of discrete solid filter'particles 36, preferably extending along substantially the'entire length of 'drill collar section 16. "These 'filterpa'it'icles desirably comprise -'gravel,which may have a xn'axi-mum particle dimension of about A". Fig. 4 illustrates schematically the manner of 'filling the gravel into the lowersection 16 of the drill collar. "As shownf'this section of the drill collaris-suspended ina conventional rotary table 37 by slips 13%, and the gravel 36 is then poured-into the suspended verticallye xtending drill collar slection about the outside of its contained pipe 30-an'd ose.

In using the apparatus of Figs. 1 to *4, 'whipstock 11 is first lowered intomain bore 1i? "of the welL-and is positioned atthelocation atwhieh a -drain-hole"14 -is desired. Thelowensection '16 ofthe flexihledrill collar is then placed-in the upperportion of 'th'e well and filled with gravel, as shown in Fig. 4, 'followingwhic'h the upper section -15 of the drill collar isattach'ed by pin and 1 'slot connection 26,- 27to thelowersectirjn ofthe drill collar, and the entire unit isthen lowered into the well atthe lower endofdrill string 118, 1 19. The flexible drill'collar and carried bit are then advanced downwardly within upper tubular portion 12 of the'whipstock and against deflecting face 13, tobe deflect'ed l'aterally'for drilling the illustrated progressively outwardly curving drainhole or accessory bore 14. A'sf'the .bit reaches "the point at Which'it'is to "drill the 'drain'liol'e,

we commence clockwise rotation of the drill string -and collar, and feed circulating fluid to the drill bit through the drill string, upper section 15 of the drill collar and hose 28.

Such rotation, downward advancement, and fluid circulation is continued untilthe bit has completed drilling of the hole, and the connection 21 between the two drill collar sections is preferably "located at substantially the juncture between the main bore and drain hole, as shown in Fig. 1. 'The'operator then turns the drill string and upper section .15- of the drill collar in a counterclockwise direction, as'seen from the surface of the earth, to break the pin and} slot connection. With the connection thus broken, the drill string and upper section 15 of the drill collar are withdrawn upwardly fromthe well, leaving the lower section 16 of the drill collar in the position of Fig. l. Whipstock 11 is then lifted out of the well, following "which the'well may be placedinproduction.

When the well is inproducti'omoil flows from the earth surrounding drain hole 14 into drill collar section 16 through itswall apertures 20, to then pass upwardly within the drill collar to the main bore 10 of the well. As theoil passes upwardlywithin the drill collar, it must flow through the relatively restricted passages formed between-the gravelparticles 36, so that the'gravel'acts to filter out any sand or other materials which may be contained'in the oil. At the-same time, the rigid walls of the drill collar segments serve to line the drain hole, and prevent inward collapse of the drain hole walls. After the well has been inproduction for-a relatively short period of time, say about two or three weeks, the well fluid disintegrates or dissolves hose 28, 'to increase the fluid passing area of the drill collar or liner.

-Fig. 5 represents the lower flexible drill collar section 16a of a variational'form of the invention. This form is essentially "the same as that previously described, except that the gravel or other filter mass 36ais carried anuularly about, rather than within, the flexible drill collar, and-the circulation hose 28a extends about the outside of the drill collar'and gravel mass. Hose 28a is of course of a-considerably larger diameter than the hose 28 of Fig. '1, and is attached to drill collar'16a at its upper and lower ends by a pair of annular clamps 29a and 33a. 'Except'for the positioning and formation of the'hose and gravel mass, the form'of-Fig. 5 is to be considered identical with that of Fig. 1. As in Fig. l, hose 28a is formed of amaterial adapted to disintegrate or dissolve in'the well fluid, which material may be any of those previously mentioned.

During drilling of a drain hole with the Fig. 5 device, hose'23a acts to-confine circulation fluid fed to the upper end of drill collar section 16a, so that the circulation fluid passes downwardly to drill bit 17a. After the hole has been drilled in thepreviously mentioned manner, the lower drill collar section "and hose shown in Fig. 5 are left in the drain hole, the well fluid from the surrounding earth formation disintegrates or dissolves hose 28a, and the'fluid then flows-through gravel 36a into drill collar section 16a for passage upwardly into the main bore of the well. The gravelyof course, serves the same filtering function attained in Fig. l.

' Obviously, in theFi'gpS arrangement, the diameter of tube 28a 'mustbe sufiicientlysmall to allow the tube to enter a hole drilled by bit 17a.

We claim:

1. Apparatus comprising an elongated longitudinally flexible tubular body having wall apertures and adapted tobe lowered into a well bore and to curve laterally thereform intoa drain hole, a head carried at the'lower end of said body, a flexible hose extending longitudinally within said body and delivering circulation'flui'd to said head during lowering, said hose being disintegrable in the well fluid flowing from the earth formation into the well, a mass offilter particles contained in said body at the outsideofsaidliose atubular upper section connected to the upper end of said body for lowering it into a well, a connection between said upper section and body preformed to be broken by manipulation of the upper section from the surface of the earth, and a connection between said upper section and the upper end of said hose adapted to be broken by manipulation of the upper section to permit upward removal of the upper section without said body and hose.

2. Apparatus as recited in claim 1, in which said connection between said upper section and the upper end of the hose comprises a pair of telescopically intertitting tubular connecting parts connected to said upper section and body respectively and relatively movable out of interfitting fluid passing interengagement upon upward withdrawal of said upper section relative to said tubular body.

3. Apparatus as recited in claim 2, in which said tubular body comprises a series of .articulately connected rigid tubular sections, and said head comprises a drill bit at the lower end of said body.

4. Apparatus comprising an apertured pipe adapted to be lowered into a well bore and through which well fluid flows when the well is in production, a mass of filter particles carried by said pipe at a location to be in the path of said fluid when the well is in production, a hose extending longitudinally of said pipe for conducting circulation fluid downwardly toward the lower end of the pipe as it is lowered into the well, an upper tubular body connected to the upper end of said pipe for lowering it into the well, a connection between said pipe and body preformed to be broken by manipulation of the body from the surface of the earth to permit removal of the body separately from said pipe, and a connection between said body and the upper end of the hose through which circulation fluid passes from said body to the hose and preformed to be broken by manipulation of the body from the surface of the earth, said hose being disintegrable by said well fluid which flows through said pipe and filter mass when the well is in production.

5. Apparatus comprising an elongated unit to be lowered into a well and constructed to be longitudinally flexible and thereby adapted to curve laterally from the main well bore into a laterally extending drain hole, said unit including an elongated longitudinally flexible apertured tubular liner through which the well fluid flows in passing from said drain hole into the main bore, a mass of filter particles carried by said tubular liner at a location to be in the path of said well fluid through the drain hole, a tubular upper section connectable to the upper end of said liner for lowering the liner into a well, a connection between said upper section and liner preformed to be broken by manipulation of the upper section from the surface of the earth to permit upward removal of the upper section without said liner and filter mass, a drill bit carried at thelower end of said liner, and a hose extending longitudinally in said liner and acting to deliver circulation fluid to said bit during lowering of the unit in a well, said filter particles being contained within said liner at the outside of said hose.

6. Apparatus comprising an elongated unit to be lowered into a well and constructed to be longitudinally flexible and thereby adapted to curve laterally from the main well bore into a laterally extending drain hole, said unit including an elongated longitudinally flexible apertured tubular liner through which the Well fluid flows in passing from said drain hole into the main bore, a mass of filter particles carried by said tubular liner at a location to be in the path of said well fluid through the drain hole, a tubular upper section connectable to the upper end of said liner for lowering the liner into a well, a connection between said upper section and liner preformed to be rolten by manipulation of the upper section from the surface of the earth to permit upward removal of the upper section without said liner and filter mass, and a hose extending longitudinally of said unit, and acting to deliver circulation fluid to the lower end of the unit during lowering of the unit in a well, said hose being constructed to disintegrate in the Well fluid.

7. Apparatus comprising an elongated unit to be lowered into a well and constructed to be longitudinally flexible and thereby adapted to curve laterally from the main well bore into a laterally extending drain hole, said unit including an elongated longitudinally flexible apertured tubular liner through which the well fluid flows in passing from said drain hole into the main bore, a mass of filter particles carried by said tubular liner at a location to be in the path of said well fluid through the drain hole, a tubular upper section connectable to the upper end of said liner for lowering the liner into a well, a connection between said upper section and liner preformed to be broken by manipulation of the upper section from the References Cited in the file of this patent UNITED STATES PATENTS 80,875 Platt et al. Aug. 11, 1868 1,342,813 Huston June 8, 1920 1,620,412 Tweeddale Mar. 8, 1927 2,211,803 Warburton Aug. 20, 1940 2,397,070

Zublin Mar. 19, 1946 

